MXPA06005474A - Continuous production of molded plastic containers - Google Patents

Abstract

A system for making plastic containers includes a source (20) for providing a continuous stream of molten plastic, and a cutter (20) for severing a continuing series of individual mold charges from the continuous molten plastic stream. A compression molder (24) includes a plurality of compression molds arranged in a continuing series for receiving the mold charges in sequence and compression molding the mold charges into a continuing series of individual plastic container preforms. A blow molder (42) includes a plurality of blow molds arranged in a continuing series for receiving the individual plastic container preforms in sequence and blow molding the preforms into a continuing series of plastic containers. A common drive (52) coordinates continuous and synchronous operation of the molten plastic source, the cutter, the compression molder and the blow molder to provide the continuing series of plastic containers from the continuous stream of molten plastic.

Description

CONTINUOUS PRODUCTION OF MOLDED PLASTIC CONTAINERS FIELD OF THE INVENTION The present invention is directed to molded plastic containers, and more particularly to a system and method for the continuous production of molten-phase polymer plastic containers.

BACKGROUND AND BRIEF DESCRIPTION OF THE INVENTION The typically blow molded plastic container preforms are produced in batch processes, in which one or more solid phase polymers such as polyethylene terephthalate (PET) are melted and injected into molds. of preform. The injection molded preforms are blow molded to form the plastic containers, usually at a later time. A general object of the present invention is to provide a system and method for the continuous production of plastic containers blow molded from molten polymer. A system for producing plastic containers in accordance with a presently preferred aspect of the invention includes a source for providing a continuous flow of molten plastic, and a cutter for separating a continuous series of individual mold loads from the continuous molten plastic stream. . A compression moulder 172886 includes a plurality of compression molds arranged in a continuous array to receive the mold loads in sequence and compression mold the mold loads in a continuous series of individual plastic container preforms. A blow molder includes a plurality of blow molds arranged in a continuous array to receive the preforms of individual plastic containers in sequence and blow-molding the preforms into a continuous series of plastic containers. A common drive coordinates the continuous and synchronized operation of the molten plastic source, the cutter, the compression moulder and the blow molder to provide the continuous series of plastic containers of molten plastic continuous current. A method of producing plastic containers in accordance with another aspect of the present invention includes providing a continuous stream of molten plastic, cutting the direct current at individual mold loads, and transferring the mold loads in sequence into a continuous series of molds. Of compression. A continuous series of plastic container preforms is compression molded into the compression molds, and transferred in sequence to a continuous series of blow molds. A continuous series of plastic containers is formed in the blow molds and removed in sequence. The step of transferring the preforms to the blow molds preferably includes the conditioning of the preforms before blow molding. A production system for plastic containers according to a third currently preferred aspect of the invention includes a source for providing a continuous stream of molten plastic, and a compression or injection molding for molding a continuous series of individual plastic container preforms. . A blow molder includes a plurality of blow molds arranged in a continuous array to receive the preforms of individual plastic containers in sequence and blow-molding the preforms into a continuous series of plastic containers. A common drive coordinates the continuous and synchronized operation of the molten plastic source, the preform moulder and the blow moulder to provide the continuous series of plastic containers of the molten plastic direct current.

BRIEF DESCRIPTION OF THE FIGURE The invention, together with the objects, features, advantages and additional aspects of it, will be better understood from the following description, the appended claim and the accompanying figure 1, which is a schematic diagram of a system for producing plastic containers according to a currently preferred embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION Figure 1 illustrates a system 10 for producing plastic containers in accordance with a currently preferred embodiment of the invention. An extruder 12 receives one or more plastic resin materials from the associated hoppers 14. The extruder 12 is driven by a motor 16 to provide a continuous stream of molten plastic resin material to an extrusion nozzle 18. The plastic resin material may comprise molten PET, for example, to make construction containers of Monolayer PET As an alternative, multiple extruders 12 can feed associated streams of molten plastic material to the nozzle 18, with the nozzle 18 being , constructed to provide a continuous stream of resin material in layers for the manufacture of multi-layer containers. Such containers may have inner and outer surface layers of PET construction, for example, and one or more intermediate layers of barrier material, such as ethylene vinyl alcohol (EVOH) or nylon, to retard the migration of gas, steam and water. / or flavorings through the wall of the container. As another alternative, the extruder 12 can be replaced by a reactor within which the resin material, such as PET, is produced by melt phase polymerization. The continuous stream of molten plastic resin is fed to a pellet cutter 20 and a transfer mechanism 22 to separate a continuous series of individual mold loads from the plastic resin direct current, and transfer the mold loads to individual molds 26 of a compression mold 24 The compression moulder 0 preferably includes a plurality of compression molds 26 arranged in a series. - continuous to receive the loading pellets in sequence and compression mold pellets into a continuous series of individual plastic container preforms. The compression molds 26 are preferably carried by a rotating turret 28, which is driven in synchronism with the rotation of the cutter 20 and transfer mechanism 22. The compression moulder 24, transfer mechanism 22 and cutter 20 0 can be as shown in FIG. discloses in U.S. Patents 5,866,177 or 6,349,838, for example, the descriptions of which are incorporated herein by reference. After the preforms have been compression molded and cooled sufficiently to retain their shape, the preforms are individually removed from the molds 26 and transferred by wheels or other suitable transfer devices 30, 32 to a conditioning stage 34. In the conditioning stage 34, the preforms are fed in a circuit 36 around a wheel 38, and then back to a preform transfer wheel 40. During the trip in the circuit 36, the preforms are allowed to cool from the temperature to which they exit the compression moulder 24 at a temperature suitable for blow molding. For example, the PET preforms can be removed from the compression moulder 24 at a temperature of about 280 to 300 ° F (136.4 to 147.-4 ° e), and are allowed to cool in the conditioning step 34. at a temperature of 210 to 220 ° F (97.9 to 103.4 ° C) suitable for blow molding. The conditioning step 34 may also include selective heating to obtain a temperature profile in the preform suitable for blow molding, and may include crystallization of portions of the preform, such as the preform finish. The conditioning stage 34 may comprise a rotating wheel or turret, or an extended conveyor circuit along which the preforms are transported. After conditioning of the preform in step 34, the preforms are transferred to a blow molder 42 by the wheel, turret or other suitable transfer device 40. The blow moulder 42 includes a continuous series of blow molds 44 mounted on a turret or the like 46 to receive the preforms in sequence, and blow molding the preforms in containers of desired geometry. (The reference to molding, compression or blow molding of the preforms or containers "in sequence" does not mean that the preforms or containers are formed one at a time In effect, the compression moulder 24 and / or blow moulder 42 preferably includes the ease of compression molding or blow molding multiple preforms and containers at each stage of the mold). The "Stroke" moulder 4 may be of the type described in US Pat. Nos. 5,683,729, 5,863,571 and 6,168,749, the disclosures of which are incorporated herein by reference. After blow molding, the containers are transferred by a wheel, turret or other suitable device 48 to a conveyor 50 to move the containers to subsequent manufacturing stages, such as labeling (decoration), filling, capping and packaging steps. As an alternative, the subsequent steps can be linked directly to the blow moulder 42 to form an integrated sequential system. The additional stages can be added to operate the finishing of the preform or container. For example, the finish may be crystallized, as illustrated for example in the Application-from the United States No. / 122,901 filed on April 12, 2002. As another example, the finishing rings can be added to the pre-finished or subsequent blow-molding neck, as described for example in US Requests Series No. 10. / 375,737, 10 / 403,415, 10 / 375,736, 10 / 351,671 and 10 / 375,758. Other forms of finishing manipulation may be implemented. A common integrated pulse / control mechanism 52 is connected to the drive mechanism 16 of the extruder 12, to the driving mechanism of the cutter 20 and transfer wheel 22, to the driving mechanism of the compression molding turret -28r al- mechanism, stage driver of conditioning 34, to the blower turret drive mechanism 46, to the drive mechanism of the conveyor 50 and to the driving mechanisms of the various transfer devices to operate and control these pulse mechanisms continuously and in synchronism for the continuous production of containers in the output of the blow moulder 42 from a molten plastic continuous stream to the outlet of the extruder 12. The pulse / control mechanism 52 may comprise electronic servo control systems for synchronizing the operation of the servo motors connected to the extruder 12, compression 28, conditioning step 34, blow molding 42 and transport or 50. As an alternative, the pulse / control mechanism 52 may comprise a single motor that is connected by suitable pulse mechanisms, such as belts, gears or chains, to the operating mechanisms of the extruder, compression moulder, conditioner , blow molder and conveyor. In any case, the extruder, preform compression moulder, preform conditioner, preform blow moulder and conveyor are continuously operated and , synchronized with each other for the continuous production of containers of the extruder's molten outlet. Therefore, a system and method for producing plastic containers that fully satisfy all the objects and purposes previously described have been described. The system and method of the invention possess a number of advantages over the prior art, including but not limited to: (1) Reduced intrinsic viscosity loss (VI) in the preform, producing better part quality and the opportunity to use low cost material. (2) Reduced energy required because the preform does not need to be reheating ambient temperature prior to blow molding. (3) Reduced cost of personalization of the system to allow the addition of modules for finishing manipulation, finishing crystallization, container decoration, filling and capping, etc. The invention has been described in together with a currently preferred embodiment, and a number of modifications and variations have been discussed. Other modifications and variations will readily be suggested by themselves to persons of ordinary skill in the art. The invention is proposed to include all modifications and variations when they fall within the spirit and broad scope of the appended claims. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (10)

1. CLAIMS Having described the invention as above, the content of the following claims is claimed as property: 1. System for producing plastic containers, characterized in that it includes: a source to provide a continuous stream of molten plastic, a cutter coupled to the source for separating a continuous series of individual mold loads from the direct current, a compression-comprising moulder including a plurality of compression molds arranged in a continuous array to receive the mold loads in sequence and compression mold the mold loads in a continuous series of individual plastic container preforms; a blow molder including a plurality of blow molds arranged in a continuous array to receive the preforms of individual plastic containers in sequence and blow-molding the preforms into a continuous series of plastic containers, and a driving mechanism or common to coordinate the continuous and synchronized operation of the source, the cutter, the compression moulder and the blow moulder.
2. 2. System according to claim 1, characterized in that it additionally includes a preform conditioner coupled to the common drive mechanism and connected between the compression moulder and the blow moulder to condition the preform molds by compression prior to blow molding in the blow molder.
3. System according to claim 2, characterized in that it additionally includes a conveyor. coupled to the common drive and connected to the blow moulder to receive the continuous series of plastic containers from the blow moulder.
4. 4. System according to claim 1, characterized in that the source includes an extruder.
5. 5. Method for producing plastic containers, characterized in that it includes the steps of: (a) providing a continuous stream of molten plastic, (b) cutting the direct current at individual mold loads, (c) transferring the mold loads in sequence to a continuous series of compression molds, (d) compression molding a continuous series of plastic container preforms in the compression molds, (e) transferring the continuous series of plastic container preforms in sequence to a continuous series of blowing molds, (f) blow molding a continuous series of plastic containers in the blow molds, (g) removing the containers in sequence from the blow molds, and (h) operating steps (a) to (h) ) in synchronism to provide a continuous series of blow molded containers of molten plastic stream.
6. 6. Method according to claim 5, characterized in that step (e) includes the conditioning of the preforms of plastic containers prior to blow molding in step (f).
7. Method according to claim 5, characterized in that it includes at least one stage, prior to step (e) or subsequent to step (g), selected from the group consisting of: crystallizing all or a portion of the finish of the preform or container, and attaching all or a portion of a finish to the preform or container.
8. Method according to claim 5, characterized in that it includes the step of attaching a label to the container during or subsequent to step (f).
9. 9. System for producing plastic containers, characterized in that it includes: a source for providing a continuous stream of molten plastic, a preform moulder for molding the plastic in a continuous series of individual plastic container preforms, a blow molder including a plurality of blow molds arranged in a continuous series to receive the preforms of individual plastic containers in sequence and blow-molding the preforms into a continuous-series of plastic-containers,--and a . common drive to coordinate the continuous and synchronized operation of the source, the preform moulder and the blow moulder.
10. 10. Method for producing plastic containers, characterized in that it includes the steps of: (a) providing a continuous stream of molten plastic, (b) molding a continuous series of preforms of plastic containers, (c) transferring the continuous series of preforms from plastic containers in sequence to a continuous series of blow molds, (d) blow molding a continuous series of plastic containers in the blow molds, (e) removing the containers in sequence from the blow molds, and ( f) operating steps (a) to (e) in synchronism to provide a continuous series of molded containers blown from the molten plastic stream.